The invention relates generally to anthelmintic formulations which can have significant parasiticidal activity as anthelmintics, ectoparasiticides, insecticides or acaricides in animal health and more particularly to solid anthelmintic formulations containing ivermectin.
Active ingredients of anthelmintics and their methods of formation in accordance with preferred embodiments of the invention are discussed in e.g. U.S. Pat. Nos. 3,502,661 and 4,199,569, the contents of which are incorporated herein by reference.
It is often beneficial, under certain circumstances, to include multiple drugs in the same formulation in order to target a wider variety of parasites. One particularly desirable anthelmintic active ingredient is ivermectin. Ivermectin is hygroscopic and therefore tends to be undesirably unstable. It has also been seen that ivermectin is unstable in both acidic and basic solutions and is susceptible to photodegradation and oxidative degradation. Accordingly, it is very difficult to prepare a solid composition, such as a tablet, containing ivermectin without having to resort to using a large amount of filler material to make up the bulk of the tablet in order to maintain the integrity of the compound. Even then, degradation problems can exist. This problem is compounded when additional drugs are intended to be included in the same formulation, as ivermectin can degrade other drugs.
Accordingly, it is desirable to provide a multidrug formulation in solid form that can be formed into a solid or tablet of optimal size, palatable to animals and which can be easily administered to the affected animal.
Another object of the invention is to provide an improved method of preparing formulations including invermectin.